| The effect of tryptophan on growth performance, behavior, stress and meat quality of Ross 308 x Ross 308 broiler chickens was examined. Diets were formulated to be isonitrogenous and isocaloric and contained 0, 2, 4 or 6 g/kg of tryptophan above the commercial levels of 2.5 g/kg for the starter, 2.2 g/kg for the grower and 1.8 g/kg for the finisher. One thousand, one hundred and twenty-eight birds were randomly placed into twenty-four floor pens and separated by sex. The trials monitored the birds from 1 to 38 days of age. Each pen of 47 birds had a tube feeder; nipple drinkers and wood shavings were used as litter material. Weight, feed intake, weight gain, feed to gain and mortality were unaffected by tryptophan. Tonic immobility (avg number of inductions needed = 2 and average duration of immobility = 146 s), H/L ratio (avg = 0.41+/-0.03), CK (avg = 2086+/-147) and postmortem pH (avg = 5.96+/-0.02) were all unaffected by level of dietary tryptophan. Breast muscle samples collected during trial 1 revealed that males fed 6 g/kg tryptophan exhibited lower protein extractability than those fed the control diet (39.8+/-3.2%, 56.1+/-2.8% respectively). SDS-PAGE gels and Western blots showed no difference in banding patterns indicating there was no change in the postmortem degradation of myosin or a reduction in glycogen phosphorylase extractability in regards to dietary treatment. Increased dietary tryptophan did not decrease preslaughter stress, or meat quality of broiler chickens. |
